C# Code:

public void ExportExcel(DataTable dt)
{
   if (dt != null)
   {
      Microsoft.Office.Interop.Excel.Application excel = new Microsoft.Office.Interop.Excel.Application();
      
      if (excel == null)
      {
         return;
      }
      
      //设置为不可见，操作在后台执行，为 true 的话会打开 Excel
      excel.Visible = false;
      
      //打开时设置为全屏显式
      //excel.DisplayFullScreen = true;
      
      //初始化工作簿
      Microsoft.Office.Interop.Excel.Workbooks workbooks = excel.Workbooks;
      
      //新增加一个工作簿，Add（）方法也可以直接传入参数 true
      Microsoft.Office.Interop.Excel.Workbook workbook = workbooks.Add(Microsoft.Office.Interop.Excel.XlWBATemplate.xlWBATWorksheet);
      //同样是新增一个工作簿，但是会弹出保存对话框
      //Microsoft.Office.Interop.Excel.Workbook workbook = excel.Application.Workbooks.Add(true);
      
      //新增加一个 Excel 表(sheet)
      Microsoft.Office.Interop.Excel.Worksheet worksheet = (Microsoft.Office.Interop.Excel.Worksheet)workbook.Worksheets[1];
      
      //设置表的名称
      worksheet.Name = dt.TableName;
      try
      {
         //创建一个单元格
         Microsoft.Office.Interop.Excel.Range range;
         
         int rowIndex = 1; //行的起始下标为 1
         int colIndex = 1; //列的起始下标为 1
         
         //设置列名
         for (int i = 0; i < dt.Columns.Count; i++)
         {
            //设置第一行，即列名
            worksheet.Cells[rowIndex, colIndex + i] = dt.Columns[i].ColumnName;
            
            //获取第一行的每个单元格
            range = worksheet.Cells[rowIndex, colIndex + i];
            
            //设置单元格的内部颜色
            range.Interior.ColorIndex = 33;
            
            //字体加粗
            range.Font.Bold = true;
            
            //设置为黑色
            range.Font.Color = 0;
            
            //设置为宋体
            range.Font.Name = "Arial";
            
            //设置字体大小
            range.Font.Size = 12;
            
            //水平居中
            range.HorizontalAlignment = Microsoft.Office.Interop.Excel.XlHAlign.xlHAlignCenter;
            
            //垂直居中
            range.VerticalAlignment = Microsoft.Office.Interop.Excel.XlVAlign.xlVAlignCenter;
         }
         
         //跳过第一行，第一行写入了列名
         rowIndex++;
         
         //写入数据
         for (int i = 0; i < dt.Rows.Count; i++)
         {
            for (int j = 0; j < dt.Columns.Count; j++)
            {
               worksheet.Cells[rowIndex + i, colIndex + j] = dt.Rows[i][j].ToString();
            }
         }
         
         //设置所有列宽为自动列宽
         //worksheet.Columns.AutoFit();
         
         //设置所有单元格列宽为自动列宽
         worksheet.Cells.Columns.AutoFit();
         //worksheet.Cells.EntireColumn.AutoFit();
         
         //是否提示，如果想删除某个sheet页，首先要将此项设为fasle。
         excel.DisplayAlerts = false;
         
         //保存写入的数据，这里还没有保存到磁盘
         workbook.Saved = true;
         
         //设置导出文件路径
         string path = HttpContext.Current.Server.MapPath("Export/");
         
         //设置新建文件路径及名称
         string savePath = path + DateTime.Now.ToString("yyyy-MM-dd-HH-mm-ss") + ".xlsx";
         
         //创建文件
         FileStream file = new FileStream(savePath, FileMode.CreateNew);
         
         //关闭释放流，不然没办法写入数据
         file.Close();
         file.Dispose();
         
         //保存到指定的路径
         workbook.SaveCopyAs(savePath);
         
         //还可以加入以下方法输出到浏览器下载
         FileInfo fileInfo = new FileInfo(savePath);
         OutputClient(fileInfo);
      }
      catch(Exception ex)
      {
         
      }
      finally
      {
         workbook.Close(false, Type.Missing, Type.Missing);
         workbooks.Close();
         
         //关闭退出
         excel.Quit();
         
         //释放 COM 对象
         Marshal.ReleaseComObject(worksheet);
         Marshal.ReleaseComObject(workbook);
         Marshal.ReleaseComObject(workbooks);
         Marshal.ReleaseComObject(excel);
         
         worksheet = null;
         workbook = null;
         workbooks = null;
         excel = null;
         
         GC.Collect();
      }
   }
}

//来源:C/S框架网(www.csframework.com) QQ:23404761